text: In 1998, the U.S. Environmental Protection Agency (U.S. EPA) concluded that the use of agricultural defoliants led to increased risks of water contamination and dangers to freshwater and marine life. High doses of tribufos were labeled as a possible carcinogen and a toxin to freshwater and marine invertebrates. Dimethipin has also been labeled as a possible human carcinogen.
  A published study in the Journal of Agricultural and Food Chemistry reported that through successive surface runoff events in defoliated cotton fields, defoliant concentrations decreased exponentially within the test area and could negatively affect marine life in the runoff zones.
  Agent Orange, a defoliant used by the United Kingdom during the Malayan Emergency in the 1950s and the United States during the Vietnam War to defoliate regions of Vietnam from 1961 to 1971, has been linked to several long-term health issues. Agent Orange contains a mixture of 2,4-D and 2,4,5-T as well as dioxin contaminants. Members of the Air Force Ranch Hand and the Army Chemical Corps who served in the Vietnam War were occupationally exposed to Agent Orange have a higher incidence of diabetes, heart disease, hypertension, and chronic respiratory diseases.
  Among other occupations, farmers are at a significantly higher risk of developing Alzheimer's disease due to a greater chance of defoliant exposure.